Many types of medical devices are designed to be implanted within the human body. Examples include stents, scaffolds, drug delivery devices, cardiac rhythm management devices, neurological stimulation devices, and the like.
Some implantable medical devices are designed to function by utilizing energy from a power source. Frequently, such devices include a battery, which is implanted into the body as part of the medical device and is typically housed within a sealed case. In many circumstances, the sealed case is made from a relatively noble metal such as titanium to prevent the exposure of the contents of the battery to the in vivo environment.
In the absence of recharging, batteries can only provide a finite amount of power before they are discharged to the point of being useless. In circumstances where a battery has been completely discharged, the battery and the associated medical device must generally be explanted and replaced by a new one, unless the battery was only intended for temporary use. For example, when the battery inside a pacemaker no longer provides sufficient power, the pacemaker must generally be surgically removed and replaced with a new pacemaker.
Unfortunately, removal of implanted devices is not always an easy task. The body's immunological response to a foreign body generally results over time in the formation of fibrous tissue around an implanted medical device. This fibrous tissue can make it difficult to remove implanted medical devices without risking harm to the patient.